What happened
On March 18, 2014, a Helitrans AS Eurocopter AS 350 B3, registration LN-OFC, was conducting a commercial transport mission near Selnesåsen in Lyngen, Troms. The mission involved transporting personnel and equipment to a telecommunications mast. After successfully delivering a 200 kg load via a 15-meter long line, the pilot returned to pick up four passengers.
As the helicopter approached the chosen landing site, which was located south of a power line, the rotor wash disturbed a layer of fresh, dry snow. This created a sudden white-out condition, causing the pilot to lose visual references. During this period of disorientation, the aircraft drifted forward unexpectedly, passing beneath the energized line. The anti-collision light mounted on the vertical fin struck the wire, causing the light to be torn from the airframe. The pilot managed to stabilize the aircraft and land safely to inspect the damage.
The investigation
The Norwegian Safety Investigation Authority (NSIA) examined the environmental conditions and the operator's procedures. Investigators noted that recent snowfall and freezing temperatures had left a significant amount of loose, dry snow on the ground, which was highly susceptible to being lofted by rotor downwash.
While the initial long-line delivery did not trigger a white-out—likely because the helicopter remained at a safe distance from the ground—the subsequent landing with passengers brought the aircraft much closer to the surface, increasing the risk. The investigation also reviewed the operator's manual, which contained procedures for managing white-out conditions, and compared the pilot's experience against company requirements for mountain flying.
Findings
- The primary cause of the incident was the white-out condition caused by the helicopter's own rotor wash, which led to a loss of visual references and an unintended forward movement.
- The pilot's flight experience was below the company's established minimum of 1,000 hours for mountain operations, as the pilot had 920 total hours.
- The chosen landing site placed the power line directly in the flight path during the approach.
- The company's operational procedures regarding landing site selection and planning for snow-prone areas were found to be insufficiently detailed.
Safety action
Following the incident, the operator began updating its documentation to improve the planning and execution of landings in areas where snow disturbance is expected.